text: # This file is part of Scapy
  # Scapy is free software: you can redistribute it and/or modify
  # it under the terms of the GNU General Public License as published by
  # the Free Software Foundation, either version 2 of the License, or
  # any later version.
  #
  # Scapy is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  # GNU General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with Scapy. If not, see <http://www.gnu.org/licenses/>.
  
  # scapy.contrib.description = Intermediate System to Intermediate System (ISIS)
  # scapy.contrib.status = loads
  
  """
      IS-IS Scapy Extension
      ~~~~~~~~~~~~~~~~~~~~~
  
      :copyright: 2014-2016 BENOCS GmbH, Berlin (Germany)
      :author:    Marcel Patzlaff, mpatzlaff@benocs.com
                  Michal Kaliszan, mkaliszan@benocs.com
      :license:   GPLv2
  
          This module is free software; you can redistribute it and/or
          modify it under the terms of the GNU General Public License
          as published by the Free Software Foundation; either version 2
          of the License, or (at your option) any later version.
  
          This module is distributed in the hope that it will be useful,
          but WITHOUT ANY WARRANTY; without even the implied warranty of
          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
          GNU General Public License for more details.
  
      :description:
  
          This module provides Scapy layers for the Intermediate System
          to Intermediate System routing protocol as defined in RFC 1195.
  
          Currently it (partially) supports the packaging/encoding
          requirements of the following RFCs:
           * RFC 1195 (only the TCP/IP related part)
           * RFC 3358 (optional checksums)
           * RFC 5301 (dynamic hostname extension)
           * RFC 5302 (domain-wide prefix distribution)
           * RFC 5303 (three-way handshake)
           * RFC 5304 (cryptographic authentication)
           * RFC 5308 (routing IPv6 with IS-IS)
  
      :TODO:
  
          - packet relations (requests, responses)
          - support for recent RFCs:
            * RFC 5305 (traffic engineering)
            * RFC 5307 (support for G-MPLS)
            * RFC 5310 (generic cryptographic authentication)
            * RFC 5316 (inter-AS MPLS and G-MPLS TE)
  
  """
  
  from __future__ import absolute_import
  import struct
  import random
  
  from scapy.config import conf
  from scapy.fields import BitField, BitFieldLenField, BoundStrLenField, \
      ByteEnumField, ByteField, ConditionalField, Field, FieldLenField, \
      FieldListField, FlagsField, IEEEFloatField, IP6PrefixField, IPField, \
      IPPrefixField, IntField, LongField, MACField, PacketListField, \
      ShortField, ThreeBytesField, XIntField, XShortField
  from scapy.packet import bind_layers, Packet
  from scapy.layers.clns import network_layer_protocol_ids, register_cln_protocol
  from scapy.layers.inet6 import IP6ListField, IP6Field
  from scapy.utils import fletcher16_checkbytes
  from scapy.volatile import RandString, RandByte
  from scapy.modules.six.moves import range
  from scapy.compat import orb, hex_bytes
  
  EXT_VERSION = "v0.0.2"
  
  
  #######################################################################
  #   ISIS Utilities + Fields                                           #
  #######################################################################
  def isis_area2str(area):
      return b"".join(hex_bytes(x) for x in area.split("."))
  
  
  def isis_str2area(s):
      if len(s) == 0:
          return ""
  
      numbytes = len(s[1:])
      fmt = "%02X" + (".%02X%02X" * (numbytes // 2)) + ("" if (numbytes % 2) == 0 else ".%02X")  # noqa: E501
      return fmt % tuple(orb(x) for x in s)
  
  
  def isis_sysid2str(sysid):
      return b"".join(hex_bytes(x) for x in sysid.split("."))
  
  
  def isis_str2sysid(s):
      return ("%02X%02X." * 3)[:-1] % tuple(orb(x) for x in s)
  
  
  def isis_nodeid2str(nodeid):
      return isis_sysid2str(nodeid[:-3]) + hex_bytes(nodeid[-2:])
  
  
  def isis_str2nodeid(s):
      return "%s.%02X" % (isis_str2sysid(s[:-1]), orb(s[-1]))
  
  
  def isis_lspid2str(lspid):
      return isis_nodeid2str(lspid[:-3]) + hex_bytes(lspid[-2:])
  
  
  def isis_str2lspid(s):
      return "%s-%02X" % (isis_str2nodeid(s[:-1]), orb(s[-1]))
  
  
  class _ISIS_IdFieldBase(Field):
      __slots__ = ["to_str", "to_id", "length"]
  
      def __init__(self, name, default, length, to_str, to_id):
          self.to_str = to_str
          self.to_id = to_id
          self.length = length
          Field.__init__(self, name, default, "%is" % length)
  
      def i2m(self, pkt, x):
          if x is None:
              return b"\0" * self.length
  
          return self.to_str(x)
  
      def m2i(self, pkt, x):
          return self.to_id(x)
  
      def any2i(self, pkt, x):
          if isinstance(x, str) and len(x) == self.length:
              return self.m2i(pkt, x)
  
          return x
  
  
  class _ISIS_RandId(RandString):
      def __init__(self, template):
          self.bytecount = template.count("*")
          self.format = template.replace("*", "%02X")
  
      def _fix(self):
          if self.bytecount == 0:
              return ""
  
          val = ()
  
          for _ in range(self.bytecount):
              val += (RandByte(),)
  
          return self.format % val
  
  
  class _ISIS_RandAreaId(_ISIS_RandId):
      def __init__(self, bytecount=None):
          self.bytecount = random.randint(1, 13) if bytecount is None else bytecount  # noqa: E501
          self.format = "%02X" + (".%02X%02X" * ((self.bytecount - 1) // 2)) + ("" if ((self.bytecount - 1) % 2) == 0 else ".%02X")  # noqa: E501
  
  
  class ISIS_AreaIdField(Field):
      __slots__ = ["length_from"]
  
      def __init__(self, name, default, length_from):
          Field.__init__(self, name, default)
          self.length_from = length_from
  
      def i2m(self, pkt, x):
          return isis_area2str(x)
  
      def m2i(self, pkt, x):
          return isis_str2area(x)
  
      def i2len(self, pkt, x):
          if x is None:
              return 0
          tmp_len = len(x)
          # l/5 is the number of dots in the Area ID
          return (tmp_len - (tmp_len // 5)) // 2
  
      def addfield(self, pkt, s, val):
          sval = self.i2m(pkt, val)
          return s + struct.pack("!%is" % len(sval), sval)
  
      def getfield(self, pkt, s):
          numbytes = self.length_from(pkt)
          return s[numbytes:], self.m2i(pkt, struct.unpack("!%is" % numbytes, s[:numbytes])[0])  # noqa: E501
  
      def randval(self):
          return _ISIS_RandAreaId()
  
  
  class ISIS_SystemIdField(_ISIS_IdFieldBase):
      def __init__(self, name, default):
          _ISIS_IdFieldBase.__init__(self, name, default, 6, isis_sysid2str, isis_str2sysid)  # noqa: E501
  
      def randval(self):
          return _ISIS_RandId("**.**.**")
  
  
  class ISIS_NodeIdField(_ISIS_IdFieldBase):
      def __init__(self, name, default):
          _ISIS_IdFieldBase.__init__(self, name, default, 7, isis_nodeid2str, isis_str2nodeid)  # noqa: E501
  
      def randval(self):
          return _ISIS_RandId("**.**.**.*")
  
  
  class ISIS_LspIdField(_ISIS_IdFieldBase):
      def __init__(self, name, default):
          _ISIS_IdFieldBase.__init__(self, name, default, 8, isis_lspid2str, isis_str2lspid)  # noqa: E501
  
      def randval(self):
          return _ISIS_RandId("**.**.**.*-*")
  
  
  class ISIS_CircuitTypeField(FlagsField):
      def __init__(self, name="circuittype", default=2, size=8,
                   names=None):
          if names is None:
              names = ["L1", "L2", "r0", "r1", "r2", "r3", "r4", "r5"]
          FlagsField.__init__(self, name, default, size, names)
  
  
  def _ISIS_GuessTlvClass_Helper(tlv_classes, defaultname, p, **kargs):
      cls = conf.raw_layer
      if len(p) >= 2:
          tlvtype = orb(p[0])
          clsname = tlv_classes.get(tlvtype, defaultname)
          cls = globals()[clsname]
  
      return cls(p, **kargs)
  
  
  class _ISIS_GenericTlv_Base(Packet):
      fields_desc = [ByteField("type", 0),
                     FieldLenField("len", None, length_of="val", fmt="B"),
                     BoundStrLenField("val", "", length_from=lambda pkt: pkt.len)]  # noqa: E501
  
      def guess_payload_class(self, p):
          return conf.padding_layer
  
  
  class ISIS_GenericTlv(_ISIS_GenericTlv_Base):
      name = "ISIS Generic TLV"
  
  
  class ISIS_GenericSubTlv(_ISIS_GenericTlv_Base):
      name = "ISIS Generic Sub-TLV"
  
  
  #######################################################################
  #   ISIS Sub-TLVs for TLVs 22, 23, 141, 222, 223                      #
  #######################################################################
  _isis_subtlv_classes_1 = {
      3: "ISIS_AdministrativeGroupSubTlv",
      4: "ISIS_LinkLocalRemoteIdentifiersSubTlv",
      6: "ISIS_IPv4InterfaceAddressSubTlv",
      8: "ISIS_IPv4NeighborAddressSubTlv",
      9: "ISIS_MaximumLinkBandwidthSubTlv",
      10: "ISIS_MaximumReservableLinkBandwidthSubTlv",
      11: "ISIS_UnreservedBandwidthSubTlv",
      12: "ISIS_IPv6InterfaceAddressSubTlv",
      13: "ISIS_IPv6NeighborAddressSubTlv",
      18: "ISIS_TEDefaultMetricSubTlv"
  }
  
  _isis_subtlv_names_1 = {
      3: "Administrative Group (Color)",
      4: "Link Local/Remote Identifiers",
      6: "IPv4 Interface Address",
      8: "IPv4 Neighbor Address",
      9: "Maximum Link Bandwidth",
      10: "Maximum Reservable Link Bandwidth",
      11: "Unreserved Bandwidth",
      12: "IPv6 Interface Address",
      13: "IPv6 Neighbor Address",
      18: "TE Default Metric"
  }
  
  
  def _ISIS_GuessSubTlvClass_1(p, **kargs):
      return _ISIS_GuessTlvClass_Helper(_isis_subtlv_classes_1, "ISIS_GenericSubTlv", p, **kargs)  # noqa: E501
  
  
  class ISIS_IPv4InterfaceAddressSubTlv(ISIS_GenericSubTlv):
      name = "ISIS IPv4 Interface Address (S)"
      fields_desc = [ByteEnumField("type", 6, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="address", fmt="B"),
                     IPField("address", "0.0.0.0")]
  
  
  class ISIS_IPv4NeighborAddressSubTlv(ISIS_GenericSubTlv):
      name = "ISIS IPv4 Neighbor Address (S)"
      fields_desc = [ByteEnumField("type", 8, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="address", fmt="B"),
                     IPField("address", "0.0.0.0")]
  
  
  class ISIS_LinkLocalRemoteIdentifiersSubTlv(ISIS_GenericSubTlv):
      name = "ISIS Link Local/Remote Identifiers (S)"
      fields_desc = [ByteEnumField("type", 4, _isis_subtlv_names_1),
                     FieldLenField("len", 8, fmt="B"),
                     IntField("localid", "0"),
                     IntField("remoteid", "0")]
  
  
  class ISIS_IPv6InterfaceAddressSubTlv(ISIS_GenericSubTlv):
      name = "ISIS IPv6 Interface Address (S)"
      fields_desc = [ByteEnumField("type", 12, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="address", fmt="B"),
                     IP6Field("address", "::")]
  
  
  class ISIS_IPv6NeighborAddressSubTlv(ISIS_GenericSubTlv):
      name = "ISIS IPv6 Neighbor Address (S)"
      fields_desc = [ByteEnumField("type", 13, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="address", fmt="B"),
                     IP6Field("address", "::")]
  
  
  class ISIS_AdministrativeGroupSubTlv(ISIS_GenericSubTlv):
      name = "Administrative Group SubTLV (Color)"
      fields_desc = [ByteEnumField("code", 3, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="admingroup", fmt="B"),
                     IPField("admingroup", "0.0.0.1")]
  
  
  class ISIS_MaximumLinkBandwidthSubTlv(ISIS_GenericSubTlv):
      name = "Maximum Link Bandwidth SubTLV"
      fields_desc = [ByteEnumField("type", 9, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="maxbw", fmt="B"),
                     IEEEFloatField("maxbw", 1000)]  # in B/s
  
  
  class ISIS_MaximumReservableLinkBandwidthSubTlv(ISIS_GenericSubTlv):
      name = "Maximum Reservable Link Bandwidth SubTLV"
      fields_desc = [ByteEnumField("type", 10, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="maxrsvbw", fmt="B"),
                     IEEEFloatField("maxrsvbw", 1000)]  # in B/s
  
  
  class ISIS_UnreservedBandwidthSubTlv(ISIS_GenericSubTlv):
      name = "Unreserved Bandwidth SubTLV"
      fields_desc = [ByteEnumField("type", 11, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="unrsvbw", fmt="B"),
                     FieldListField("unrsvbw", [1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000], IEEEFloatField("", 1000), count_from=lambda pkt: pkt.len / 4)]  # in B/s  # noqa: E501
  
  
  class ISIS_TEDefaultMetricSubTlv(ISIS_GenericSubTlv):
      name = "TE Default Metric SubTLV"
      fields_desc = [ByteEnumField("type", 18, _isis_subtlv_names_1),
                     FieldLenField("len", None, length_of="temetric", adjust=lambda pkt, x:x - 1, fmt="B"),  # noqa: E501
                     ThreeBytesField("temetric", 1000)]
  
  
  #######################################################################
  #   ISIS Sub-TLVs for TLVs 135, 235, 236, and 237                     #
  #######################################################################
  _isis_subtlv_classes_2 = {
      1: "ISIS_32bitAdministrativeTagSubTlv",
      2: "ISIS_64bitAdministrativeTagSubTlv"
  }
  
  _isis_subtlv_names_2 = {
      1: "32-bit Administrative Tag",
      2: "64-bit Administrative Tag"
  }
  
  
  def _ISIS_GuessSubTlvClass_2(p, **kargs):
      return _ISIS_GuessTlvClass_Helper(_isis_subtlv_classes_2, "ISIS_GenericSubTlv", p, **kargs)  # noqa: E501
  
  
  class ISIS_32bitAdministrativeTagSubTlv(ISIS_GenericSubTlv):
      name = "ISIS 32-bit Administrative Tag (S)"
      fields_desc = [ByteEnumField("type", 1, _isis_subtlv_names_2),
                     FieldLenField("len", None, length_of="tags", fmt="B"),
                     FieldListField("tags", [], IntField("", 0), count_from=lambda pkt: pkt.len // 4)]  # noqa: E501
  
  
  class ISIS_64bitAdministrativeTagSubTlv(ISIS_GenericSubTlv):
      name = "ISIS 64-bit Administrative Tag (S)"
      fields_desc = [ByteEnumField("type", 2, _isis_subtlv_names_2),
                     FieldLenField("len", None, length_of="tags", fmt="B"),
                     FieldListField("tags", [], LongField("", 0), count_from=lambda pkt: pkt.len // 8)]  # noqa: E501
  
  
  #######################################################################
  #   ISIS TLVs                                                         #
  #######################################################################
  _isis_tlv_classes = {
      1: "ISIS_AreaTlv",
      2: "ISIS_IsReachabilityTlv",
      6: "ISIS_IsNeighbourTlv",
      8: "ISIS_PaddingTlv",
      9: "ISIS_LspEntryTlv",
      10: "ISIS_AuthenticationTlv",
      12: "ISIS_ChecksumTlv",
      14: "ISIS_BufferSizeTlv",
      22: "ISIS_ExtendedIsReachabilityTlv",
      128: "ISIS_InternalIpReachabilityTlv",
      129: "ISIS_ProtocolsSupportedTlv",
      130: "ISIS_ExternalIpReachabilityTlv",
      132: "ISIS_IpInterfaceAddressTlv",
      135: "ISIS_ExtendedIpReachabilityTlv",
      137: "ISIS_DynamicHostnameTlv",
      232: "ISIS_Ipv6InterfaceAddressTlv",
      236: "ISIS_Ipv6ReachabilityTlv",
      240: "ISIS_P2PAdjacencyStateTlv"
  }
  
  _isis_tlv_names = {
      1: "Area TLV",
      2: "IS Reachability TLV",
      6: "IS Neighbour TLV",
      7: "Instance Identifier TLV",
      8: "Padding TLV",
      9: "LSP Entries TLV",
      10: "Authentication TLV",
      12: "Optional Checksum TLV",
      13: "Purge Originator Identification TLV",
      14: "LSP Buffer Size TLV",
      22: "Extended IS-Reachability TLV",
      23: "IS Neighbour Attribute TLV",
      24: "IS Alias ID",
      128: "IP Internal Reachability TLV",
      129: "Protocols Supported TLV",
      130: "IP External Reachability TLV",
      131: "Inter-Domain Routing Protocol Information TLV",
      132: "IP Interface Address TLV",
      134: "Traffic Engineering Router ID TLV",
      135: "Extended IP Reachability TLV",
      137: "Dynamic Hostname TLV",
      138: "GMPLS Shared Risk Link Group TLV",
      139: "IPv6 Shared Risk Link Group TLV",
      140: "IPv6 Traffic Engineering Router ID TLV",
      141: "Inter-AS Reachability Information TLV",
      142: "Group Address TLV",
      143: "Multi-Topology-Aware Port Capability TLV",
      144: "Multi-Topology Capability TLV",
      145: "TRILL Neighbour TLV",
      147: "MAC-Reachability TLV",
      148: "BFD-Enabled TLV",
      211: "Restart TLV",
      222: "Multi-Topology Intermediate Systems TLV",
      223: "Multi-Topology IS Neighbour Attributes TLV",
      229: "Multi-Topology TLV",
      232: "IPv6 Interface Address TLV",
      233: "IPv6 Global Interface Address TLV",
      235: "Multi-Topology IPv4 Reachability TLV",
      236: "IPv6 Reachability TLV",
      237: "Multi-Topology IPv6 Reachability TLV",
      240: "Point-to-Point Three-Way Adjacency TLV",
      242: "IS-IS Router Capability TLV",
      251: "Generic Information TLV"
  }
  
  
  def _ISIS_GuessTlvClass(p, **kargs):
      return _ISIS_GuessTlvClass_Helper(_isis_tlv_classes, "ISIS_GenericTlv", p, **kargs)  # noqa: E501
  
  
  class ISIS_AreaEntry(Packet):
      name = "ISIS Area Entry"
      fields_desc = [FieldLenField("arealen", None, length_of="areaid", fmt="B"),
                     ISIS_AreaIdField("areaid", "49", length_from=lambda pkt: pkt.arealen)]  # noqa: E501
  
      def extract_padding(self, s):
          return "", s
  
  
  class ISIS_AreaTlv(ISIS_GenericTlv):
      name = "ISIS Area TLV"
      fields_desc = [ByteEnumField("type", 1, _isis_tlv_names),
                     FieldLenField("len", None, length_of="areas", fmt="B"),
                     PacketListField("areas", [], ISIS_AreaEntry, length_from=lambda x: x.len)]  # noqa: E501
  
  
  class ISIS_AuthenticationTlv(ISIS_GenericTlv):
      name = "ISIS Authentication TLV"
      fields_desc = [ByteEnumField("type", 10, _isis_tlv_names),
                     FieldLenField("len", None, length_of="password", adjust=lambda pkt, x: x + 1, fmt="B"),  # noqa: E501
                     ByteEnumField("authtype", 1, {1: "Plain", 17: "HMAC-MD5"}),
                     BoundStrLenField("password", "", maxlen=254, length_from=lambda pkt: pkt.len - 1)]  # noqa: E501
  
  
  class ISIS_BufferSizeTlv(ISIS_GenericTlv):
      name = "ISIS Buffer Size TLV"
      fields_desc = [ByteEnumField("type", 14, _isis_tlv_names),
                     ByteField("len", 2),
                     ShortField("lspbuffersize", 1497)]
  
  
  class ISIS_ChecksumTlv(ISIS_GenericTlv):
      name = "ISIS Optional Checksum TLV"
      fields_desc = [ByteEnumField("type", 12, _isis_tlv_names),
                     ByteField("len", 2),
                     XShortField("checksum", None)]
  
  
  class ISIS_DynamicHostnameTlv(ISIS_GenericTlv):
      name = "ISIS Dynamic Hostname TLV"
      fields_desc = [ByteEnumField("type", 137, _isis_tlv_names),
                     FieldLenField("len", None, length_of="hostname", fmt="B"),
                     BoundStrLenField("hostname", "", length_from=lambda pkt: pkt.len)]  # noqa: E501
  
  
  class ISIS_ExtendedIpPrefix(Packet):
      name = "ISIS Extended IP Prefix"
      fields_desc = [
          IntField("metric", 1),
          BitField("updown", 0, 1),
          BitField("subtlvindicator", 0, 1),
          BitFieldLenField("pfxlen", None, 6, length_of="pfx"),
          IPPrefixField("pfx", None, wordbytes=1, length_from=lambda x: x.pfxlen),  # noqa: E501
          ConditionalField(FieldLenField("subtlvslen", None, length_of="subtlvs", fmt="B"), lambda pkt: pkt.subtlvindicator == 1),  # noqa: E501
          ConditionalField(PacketListField("subtlvs", [], _ISIS_GuessSubTlvClass_2, length_from=lambda x: x.subtlvslen), lambda pkt: pkt.subtlvindicator == 1)  # noqa: E501
      ]
  
      def extract_padding(self, s):
          return "", s
  
  
  class ISIS_TERouterIDTlv(ISIS_GenericTlv):
      name = "ISIS TE Router ID TLV"
      fields_desc = [ByteEnumField("type", 134, _isis_tlv_names),
                     FieldLenField("len", None, length_of="routerid", fmt="B"),
                     IPField("routerid", "0.0.0.0")]
  
  
  class ISIS_ExtendedIpReachabilityTlv(ISIS_GenericTlv):
      name = "ISIS Extended IP Reachability TLV"
      fields_desc = [ByteEnumField("type", 135, _isis_tlv_names),
                     FieldLenField("len", None, length_of="pfxs", fmt="B"),
                     PacketListField("pfxs", [], ISIS_ExtendedIpPrefix, length_from=lambda pkt: pkt.len)]  # noqa: E501
  
  
  class ISIS_ExtendedIsNeighbourEntry(Packet):
      name = "ISIS Extended IS Neighbour Entry"
      fields_desc = [
          ISIS_NodeIdField("neighbourid", "0102.0304.0506.07"),
          ThreeBytesField("metric", 1),
          FieldLenField("subtlvslen", None, length_of="subtlvs", fmt="B"),
          PacketListField("subtlvs", [], _ISIS_GuessSubTlvClass_1, length_from=lambda x: x.subtlvslen)  # noqa: E501
      ]
  
      def extract_padding(self, s):
          return "", s
  
  
  class ISIS_ExtendedIsReachabilityTlv(ISIS_GenericTlv):
      name = "ISIS Extended IS Reachability TLV"
      fields_desc = [ByteEnumField("type", 22, _isis_tlv_names),
                     FieldLenField("len", None, length_of="neighbours", fmt="B"),
                     PacketListField("neighbours", [], ISIS_ExtendedIsNeighbourEntry, length_from=lambda x: x.len)]  # noqa: E501
  
  
  class ISIS_IpInterfaceAddressTlv(ISIS_GenericTlv):
      name = "ISIS IP Interface Address TLV"
      fields_desc = [ByteEnumField("type", 132, _isis_tlv_names),
                     FieldLenField("len", None, length_of="addresses", fmt="B"),
                     FieldListField("addresses", [], IPField("", "0.0.0.0"), count_from=lambda pkt: pkt.len // 4)]  # noqa: E501
  
  
  class ISIS_Ipv6InterfaceAddressTlv(ISIS_GenericTlv):
      name = "ISIS IPv6 Interface Address TLV"
      fields_desc = [
          ByteEnumField("type", 232, _isis_tlv_names),
          FieldLenField("len", None, length_of="addresses", fmt="B"),
          IP6ListField("addresses", [], count_from=lambda pkt: pkt.len // 16)
      ]
  
  
  class ISIS_Ipv6Prefix(Packet):
      name = "ISIS IPv6 Prefix"
      fields_desc = [
          IntField("metric", 1),
          BitField("updown", 0, 1),
          BitField("external", 0, 1),
          BitField("subtlvindicator", 0, 1),
          BitField("reserved", 0, 5),
          FieldLenField("pfxlen", None, length_of="pfx", fmt="B"),
          IP6PrefixField("pfx", None, wordbytes=1, length_from=lambda x: x.pfxlen),  # noqa: E501
          ConditionalField(FieldLenField("subtlvslen", None, length_of="subtlvs", fmt="B"), lambda pkt: pkt.subtlvindicator == 1),  # noqa: E501
          ConditionalField(PacketListField("subtlvs", [], _ISIS_GuessSubTlvClass_2, length_from=lambda x: x.subtlvslen), lambda pkt: pkt.subtlvindicator == 1)  # noqa: E501
      ]
  
      def extract_padding(self, s):
          return "", s
  
  
  class ISIS_Ipv6ReachabilityTlv(ISIS_GenericTlv):
      name = "ISIS IPv6 Reachability TLV"
      fields_desc = [ByteEnumField("type", 236, _isis_tlv_names),
                     FieldLenField("len", None, length_of="pfxs", fmt="B"),
                     PacketListField("pfxs", [], ISIS_Ipv6Prefix, length_from=lambda pkt: pkt.len)]  # noqa: E501
  
  
  class ISIS_IsNeighbourTlv(ISIS_GenericTlv):
      name = "ISIS IS Neighbour TLV"
      fields_desc = [ByteEnumField("type", 6, _isis_tlv_names),
                     FieldLenField("len", None, length_of="neighbours", fmt="B"),
                     FieldListField("neighbours", [], MACField("", "00.00.00.00.00.00"), count_from=lambda pkt: pkt.len // 6)]  # noqa: E501
  
  
  class ISIS_LspEntry(Packet):
      name = "ISIS LSP Entry"
      fields_desc = [ShortField("lifetime", 1200),
                     ISIS_LspIdField("lspid", "0102.0304.0506.07-08"),
                     XIntField("seqnum", 0x00000001),
                     XShortField("checksum", None)]
  
      def extract_padding(self, s):
          return "", s
  
  
  class ISIS_LspEntryTlv(ISIS_GenericTlv):
      name = "ISIS LSP Entry TLV"
      fields_desc = [
          ByteEnumField("type", 9, _isis_tlv_names),
          FieldLenField("len", None, length_of="entries", fmt="B"),
          PacketListField("entries", [], ISIS_LspEntry, count_from=lambda pkt: pkt.len // 16)  # noqa: E501
      ]
  
  
  class _AdjacencyStateTlvLenField(Field):
      def i2m(self, pkt, x):
          if pkt.neighbourextlocalcircuitid is not None:
              return 15
  
          if pkt.neighboursystemid is not None:
              return 11
  
          if pkt.extlocalcircuitid is not None:
              return 5
  
          return 1
  
  
  class ISIS_P2PAdjacencyStateTlv(ISIS_GenericTlv):
      name = "ISIS P2P Adjacency State TLV"
      fields_desc = [ByteEnumField("type", 240, _isis_tlv_names),
                     _AdjacencyStateTlvLenField("len", None, fmt="B"),
                     ByteEnumField("state", "Down", {0x2: "Down", 0x1: "Initialising", 0x0: "Up"}),  # noqa: E501
                     ConditionalField(IntField("extlocalcircuitid", None), lambda pkt: pkt.len >= 5),  # noqa: E501
                     ConditionalField(ISIS_SystemIdField("neighboursystemid", None), lambda pkt: pkt.len >= 11),  # noqa: E501
                     ConditionalField(IntField("neighbourextlocalcircuitid", None), lambda pkt: pkt.len == 15)]  # noqa: E501
  
  
  # TODO dynamically allocate sufficient size
  class ISIS_PaddingTlv(ISIS_GenericTlv):
      name = "ISIS Padding TLV"
      fields_desc = [
          ByteEnumField("type", 8, _isis_tlv_names),
          FieldLenField("len", None, length_of="padding", fmt="B"),
          BoundStrLenField("padding", "", length_from=lambda pkt: pkt.len)
      ]
  
  
  class ISIS_ProtocolsSupportedTlv(ISIS_GenericTlv):
      name = "ISIS Protocols Supported TLV"
      fields_desc = [
          ByteEnumField("type", 129, _isis_tlv_names),
          FieldLenField("len", None, count_of="nlpids", fmt="B"),
          FieldListField("nlpids", [], ByteEnumField("", "IPv4", network_layer_protocol_ids), count_from=lambda pkt: pkt.len)  # noqa: E501
      ]
  
  
  #######################################################################
  #   ISIS Old-Style TLVs                                               #
  #######################################################################
  
  class ISIS_IpReachabilityEntry(Packet):
      name = "ISIS IP Reachability"
      fields_desc = [ByteField("defmetric", 1),
                     ByteField("delmetric", 0x80),
                     ByteField("expmetric", 0x80),
                     ByteField("errmetric", 0x80),
                     IPField("ipaddress", "0.0.0.0"),
                     IPField("subnetmask", "255.255.255.255")]
  
      def extract_padding(self, s):
          return "", s
  
  
  class ISIS_InternalIpReachabilityTlv(ISIS_GenericTlv):
      name = "ISIS Internal IP Reachability TLV"
      fields_desc = [
          ByteEnumField("type", 128, _isis_tlv_names),
          FieldLenField("len", None, length_of="entries", fmt="B"),
          PacketListField("entries", [], ISIS_IpReachabilityEntry, count_from=lambda x: x.len // 12)  # noqa: E501
      ]
  
  
  class ISIS_ExternalIpReachabilityTlv(ISIS_GenericTlv):
      name = "ISIS External IP Reachability TLV"
      fields_desc = [
          ByteEnumField("type", 130, _isis_tlv_names),
          FieldLenField("len", None, length_of="entries", fmt="B"),
          PacketListField("entries", [], ISIS_IpReachabilityEntry, count_from=lambda x: x.len // 12)  # noqa: E501
      ]
  
  
  class ISIS_IsReachabilityEntry(Packet):
      name = "ISIS IS Reachability"
      fields_desc = [ByteField("defmetric", 1),
                     ByteField("delmetric", 0x80),
                     ByteField("expmetric", 0x80),
                     ByteField("errmetric", 0x80),
                     ISIS_NodeIdField("neighbourid", "0102.0304.0506.07")]
  
      def extract_padding(self, s):
          return "", s
  
  
  class ISIS_IsReachabilityTlv(ISIS_GenericTlv):
      name = "ISIS IS Reachability TLV"
      fields_desc = [
          ByteEnumField("type", 2, _isis_tlv_names),
          FieldLenField("len", None, fmt="B", length_of="neighbours", adjust=lambda pkt, x: x + 1),  # noqa: E501
          ByteField("virtual", 0),
          PacketListField("neighbours", [], ISIS_IsReachabilityEntry, count_from=lambda x: (x.len - 1) // 11)  # noqa: E501
      ]
  
  
  #######################################################################
  #   ISIS PDU Packets                                                  #
  #######################################################################
  _isis_pdu_names = {
      15: "L1 LAN Hello",
      16: "L2 LAN Hello",
      17: "P2P Hello",
      18: "L1 LSP",
      20: "L2 LSP",
      24: "L1 CSNP",
      25: "L2 CSNP",
      26: "L1 PSNP",
      27: "L2 PSNP"
  }
  
  
  class ISIS_CommonHdr(Packet):
      name = "ISIS Common Header"
      fields_desc = [
          ByteEnumField("nlpid", 0x83, network_layer_protocol_ids),
          ByteField("hdrlen", None),
          ByteField("version", 1),
          ByteField("idlen", 0),
          ByteEnumField("pdutype", None, _isis_pdu_names),
          ByteField("pduversion", 1),
          ByteField("hdrreserved", 0),
          ByteField("maxareaaddr", 0)
      ]
  
      def post_build(self, pkt, pay):
          # calculating checksum if requested
          pdu = pkt + pay
          checksumInfo = self[1].checksum_info(self.hdrlen)
  
          if checksumInfo is not None:
              (cbegin, cpos) = checksumInfo
              checkbytes = fletcher16_checkbytes(pdu[cbegin:], (cpos - cbegin))
              pdu = pdu[:cpos] + checkbytes + pdu[cpos + 2:]
  
          return pdu
  
  
  class _ISIS_PduBase(Packet):
      def checksum_info(self, hdrlen):
          checksumPosition = hdrlen
          for tlv in self.tlvs:
              if isinstance(tlv, ISIS_ChecksumTlv):
                  checksumPosition += 2
                  return (0, checksumPosition)
              else:
                  checksumPosition += len(tlv)
  
          return None
  
      def guess_payload_class(self, p):
          return conf.padding_layer
  
  
  class _ISIS_PduLengthField(FieldLenField):
      def __init__(self):
          FieldLenField.__init__(self, "pdulength", None, length_of="tlvs", adjust=lambda pkt, x: x + pkt.underlayer.hdrlen)  # noqa: E501
  
  
  class _ISIS_TlvListField(PacketListField):
      def __init__(self):
          PacketListField.__init__(self, "tlvs", [], _ISIS_GuessTlvClass, length_from=lambda pkt: pkt.pdulength - pkt.underlayer.hdrlen)  # noqa: E501
  
  
  class _ISIS_LAN_HelloBase(_ISIS_PduBase):
      fields_desc = [
          ISIS_CircuitTypeField(),
          ISIS_SystemIdField("sourceid", "0102.0304.0506"),
          ShortField("holdingtime", 30),
          _ISIS_PduLengthField(),
          ByteField("priority", 1),
          ISIS_NodeIdField("lanid", "0000.0000.0000.00"),
          _ISIS_TlvListField()
      ]
  
  
  class ISIS_L1_LAN_Hello(_ISIS_LAN_HelloBase):
      name = "ISIS L1 LAN Hello PDU"
  
  
  class ISIS_L2_LAN_Hello(_ISIS_LAN_HelloBase):
      name = "ISIS L2 LAN Hello PDU"
  
  
  class ISIS_P2P_Hello(_ISIS_PduBase):
      name = "ISIS Point-to-Point Hello PDU"
  
      fields_desc = [
          ISIS_CircuitTypeField(),
          ISIS_SystemIdField("sourceid", "0102.0304.0506"),
          ShortField("holdingtime", 30),
          _ISIS_PduLengthField(),
          ByteField("localcircuitid", 0),
          _ISIS_TlvListField()
      ]
  
  
  class _ISIS_LSP_Base(_ISIS_PduBase):
      fields_desc = [
          _ISIS_PduLengthField(),
          ShortField("lifetime", 1199),
          ISIS_LspIdField("lspid", "0102.0304.0506.00-00"),
          XIntField("seqnum", 0x00000001),
          XShortField("checksum", None),
          FlagsField("typeblock", 0x03, 8, ["L1", "L2", "OL", "ADef", "ADel", "AExp", "AErr", "P"]),  # noqa: E501
          _ISIS_TlvListField()
      ]
  
      def checksum_info(self, hdrlen):
          if self.checksum is not None:
              return None
  
          return (12, 24)
  
  
  def _lsp_answers(lsp, other, clsname):
      # TODO
      return 0
  
  
  class ISIS_L1_LSP(_ISIS_LSP_Base):
      name = "ISIS L1 Link State PDU"
  
      def answers(self, other):
          return _lsp_answers(self, other, "ISIS_L1_PSNP")
  
  
  class ISIS_L2_LSP(_ISIS_LSP_Base):
      name = "ISIS L2 Link State PDU"
  
      def answers(self, other):
          return _lsp_answers(self, other, "ISIS_L2_PSNP")
  
  
  class _ISIS_CSNP_Base(_ISIS_PduBase):
      fields_desc = [
          _ISIS_PduLengthField(),
          ISIS_NodeIdField("sourceid", "0102.0304.0506.00"),
          ISIS_LspIdField("startlspid", "0000.0000.0000.00-00"),
          ISIS_LspIdField("endlspid", "FFFF.FFFF.FFFF.FF-FF"),
          _ISIS_TlvListField()
      ]
  
  
  def _snp_answers(snp, other, clsname):
      # TODO
      return 0
  
  
  class ISIS_L1_CSNP(_ISIS_CSNP_Base):
      name = "ISIS L1 Complete Sequence Number Packet"
  
      def answers(self, other):
          return _snp_answers(self, other, "ISIS_L1_LSP")
  
  
  class ISIS_L2_CSNP(_ISIS_CSNP_Base):
      name = "ISIS L2 Complete Sequence Number Packet"
  
      def answers(self, other):
          return _snp_answers(self, other, "ISIS_L2_LSP")
  
  
  class _ISIS_PSNP_Base(_ISIS_PduBase):
      fields_desc = [
          _ISIS_PduLengthField(),
          ISIS_NodeIdField("sourceid", "0102.0304.0506.00"),
          _ISIS_TlvListField()
      ]
  
  
  class ISIS_L1_PSNP(_ISIS_PSNP_Base):
      name = "ISIS L1 Partial Sequence Number Packet"
  
      def answers(self, other):
          return _snp_answers(self, other, "ISIS_L1_LSP")
  
  
  class ISIS_L2_PSNP(_ISIS_PSNP_Base):
      name = "ISIS L2 Partial Sequence Number Packet"
  
      def answers(self, other):
          return _snp_answers(self, other, "ISIS_L2_LSP")
  
  
  register_cln_protocol(0x83, ISIS_CommonHdr)
  bind_layers(ISIS_CommonHdr, ISIS_L1_LAN_Hello, hdrlen=27, pdutype=15)
  bind_layers(ISIS_CommonHdr, ISIS_L2_LAN_Hello, hdrlen=27, pdutype=16)
  bind_layers(ISIS_CommonHdr, ISIS_P2P_Hello, hdrlen=20, pdutype=17)
  bind_layers(ISIS_CommonHdr, ISIS_L1_LSP, hdrlen=27, pdutype=18)
  bind_layers(ISIS_CommonHdr, ISIS_L2_LSP, hdrlen=27, pdutype=20)
  bind_layers(ISIS_CommonHdr, ISIS_L1_CSNP, hdrlen=33, pdutype=24)
  bind_layers(ISIS_CommonHdr, ISIS_L2_CSNP, hdrlen=33, pdutype=25)
  bind_layers(ISIS_CommonHdr, ISIS_L1_PSNP, hdrlen=17, pdutype=26)
  bind_layers(ISIS_CommonHdr, ISIS_L2_PSNP, hdrlen=17, pdutype=27)
  